The present disclosure generally relates to a semiconductor circuit, and particularly to a semiconductor circuit including an attenuator for reducing a phase difference between transmission phase and attenuation phase of a signal, and a method of designing such a circuit.
Amplitude control circuits such as variable attenuators have been one of the key components in many electronic circuit systems, such as an automatic gain control component in transmitter/receiver systems and an amplitude weighting component in phased-array radars. In phased-array antennas and beam-forming systems, accurate and wide amplitude control is required to adjust the side lobe levels and null points precisely. Constant transmission phase during amplitude control is required to avoid tracking errors and complex phase/amplitude calibrations.
Various digital attenuators have been previously proposed. In other types of attenuators known in the art, however, attempts to reduce variations in phase between a transmission signal and an attenuated signal tend to result in significant increase in the insertion loss and the design complexity.